Study population
The cohort enrolment criteria included children aged 0-18 months admitted to the “P. & A. Kyriakou” Children’s Hospital of Athens, a comprehensive urban pediatric tertiary care center, with a primary diagnosis of bronchiolitis infection. Specifically, the first lower respiratory infection, recognized as bronchiolitis, should be associated with at least one of the following parameters: history of cough and rhinitis, wheezing, crackles, tachypnea, use of accessory muscles and/or nasal flaring, low oxygen saturation, cyanosis with/without fever.
The exclusion criteria were: premature birth <34 weeks’ gestation, previous history of wheezing, chronic lung disease, congenital heart disease, neurodevelopmental disorders, immunodeficiency and immunosuppression.